Re: [PATCH v3 1/7] wifi: orinoco: Avoid clashing function prototypes

[Kees Cook]

On Tue, Nov 08, 2022 at 02:21:24PM -0600, Gustavo A. R. Silva wrote:
> When built with Control Flow Integrity, function prototypes between
> caller and function declaration must match. These mismatches are visible
> at compile time with the new -Wcast-function-type-strict in Clang[1].
> 
> Fix a total of 43 warnings like these:
> 
> drivers/net/wireless/intersil/orinoco/wext.c:1379:27: warning: cast from 'int (*)(struct net_device *, struct iw_request_info *, struct iw_param *, char *)' to 'iw_handler' (aka 'int (*)(struct net_device *, struct iw_request_info *, union iwreq_data *, char *)') converts to incompatible function type [-Wcast-function-type-strict]
>         IW_HANDLER(SIOCGIWPOWER,        (iw_handler)orinoco_ioctl_getpower),
>                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> The orinoco Wireless Extension handler callbacks (iw_handler) use a
> union for the data argument. Actually use the union and perform explicit
> member selection in the function body instead of having a function
> prototype mismatch. No significant binary differences were seen
> before/after changes.
> 
> These changes were made partly manually and partly with the help of
> Coccinelle.
> 
> Link: https://github.com/KSPP/linux/issues/234
> Link: https://reviews.llvm.org/D134831 [1]
> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook